Health status of the workers using mechanized hand tools in an electric parts' maker

The aim was to clarify the relations between the health status of the workers operating mechanized hand tools (MT). MT included electric drivers and air drivers, and the working conditions in an electric parts' maker. Fifty-nine female workers underwent the special examination for vibration hazards, made up of 39 MT operators (Group A) and 20 controls (Group B) who worked without MT at the same plant. The authors made questions about their health and working conditions and physical examinations. The measured items of the peripheral nervous system were the vibratory sensation and sensory nerve conduction velocity (SNCV) in the hand and arm. Those of the musculoskeletal function were pinching power, grasping power, back strength, and tapping ability. The frequency of the complaints "tingling of hands" and "numbness of hands" and "difficulty of finger extension" in Group A was significantly higher than in Group B. The frequency of "swelling of hands" and "heavy feeling of arms" in Group A had a higher tendency than in Group B. There was no difference in the results of physical examinations and vibratory sensation. Pinching power and grasping power (both hands) and back strength in Group A was greater than in Group B. Median SNCV in the hand in Group A was significantly slower than in Group B. The maximum vibration acceleration level (0.56-1.8 m/s2) of the MT used at the plant did not exceed the exposure guideline of ISO. The results suggest that although the vibration level was low enough, physiological changes appeared in the workers with MT.